底物普适性
芳基溴/碘化物：苯环含醚（3a，93%）、酯基（3g，72%）、醛基（3i，65%）、氰基（3k，60%）、二氧戊环（3i，80%）等均可兼容。
空间位阻：邻位取代底物（如2-溴甲苯，3m，72%）有效；2,6-二取代物不反应。
杂芳环：吡啶（3v，63%）、噻吩（3s，70%）、喹啉（3t，70%）等成功转化。
氘代实验：Et₃SiD参与反应得氘代醛（3x，77%），证实硅烷是氢供体。
反应机理
假设验证：糖精（pKₐ=1.6）弱亲核性可避免与酰基钯物种竞争（对比酚类）。中间体可能是酰基糖精（如6→3b，钯催化还原收率64%）。
双路径机制： 路径1，酰基钯物种直接与Et₃SiH反应生成醛。 路径2（主要路径），酰基钯与糖精形成酰基糖精中间体（如7），再经钯催化还原为醛。
Na2CO3将N-甲酰基糖精（ 2d）转化为糖精钠和CO。随后，糖精钠与由 1b的氧化加成和CO插入形成的 酰基钯物种C结合，从而生成 D。钯介导的可逆还原消除/氧化加成发生在6与D之间，随后 D与Et3SiH反应生成3b和活性钯物种A（ 路径2）。然而，原假设中提到的替代机制（ 路径1）仍不能排除。在这种路径下， C无需糖精钠参与可直接被Et3SiH还原生成 3b。
实验操作
A typical experimental procedure for reductive carbonylation of 1bwith N-formylsaccharin. Pd(OAc)2 (10.1 mg, 0.045 mmol, 3.0 mol%), dppb (28.8 mg,0.068 mmol, 4.5 mol%), 2d (475 mg, 2.25 mmol, 1.5 equiv), and Na2CO3 (238 mg, 2.25 mmol, 1.5 equiv) were added to a 30 mL test tube, which was then evacuated and backfilled three times with N2. A degassed solution of 1b (158 mL, 1.50 mmol) and Et3SiH (311 mL, 1.95 mmol, 1.3 equiv) in DMF (6 mL) was added to the test tube under N2. The tube was immediately sealed by a plastic screw cap and the mixture was stirred for 10 min at RT (this stirring is critical for the selectivity of the reaction). The mixture was subsequently warmed to 75oC and stirred for a further 16 h. The reaction mixture was cooled to RT, then diluted with Et2O (15 mL), and washed with H2O (15 mL). The aqueous layer was extracted two times with Et2O (15 mL). The combined organic layer was dried over MgSO4, filtered, and concentrated. The obtained residue was purified by flash column chromatography on silica gel (3–5% Et2O in npentane) to provide 3b as a colorless oil (132 mg,83%).
本文开发了一种无CO气体的钯催化芳基溴化物还原羰基化新方法，使用N-甲酰基糖精（2d） 作为高效CO源。该反应仅需1.5当量CO源和中等温度条件，适用于多种芳基溴化物（含敏感官能团及杂芳环）。相较于现有CO替代物，2d具有廉价、易得、稳定、高活性等优势。
参考资料：Palladium-Catalyzed Reductive Carbonylation of Aryl Halides with N-Formylsaccharin as a CO Source；Tsuyoshi Ueda, Hideyuki Konishi, and Kei Manabe； Angew. Chem. Int. Ed.2013, 52, 8611 –8615。
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